U.S. patent application number 12/303325 was filed with the patent office on 2009-10-01 for coin discriminating device.
This patent application is currently assigned to PANASONIC CORPORATION. Invention is credited to Kouji Ikeda, Satoshi Miyauchi, Takehiko Nara, Tooru Ueki.
Application Number | 20090242354 12/303325 |
Document ID | / |
Family ID | 39606674 |
Filed Date | 2009-10-01 |
United States Patent
Application |
20090242354 |
Kind Code |
A1 |
Miyauchi; Satoshi ; et
al. |
October 1, 2009 |
COIN DISCRIMINATING DEVICE
Abstract
A coin discriminating device has a detecting part, a first
switching part, a storage part, and a control part. The detecting
part has a first sensor including a pair of coils, and an
oscillating circuit, and is supplied with voltage from a power
source, and in addition, outputs a detection signal varied by a
coin passing between the coils. The first switching part switches
magnetic connection of the coils between an in-phase connection and
a reversed-phase connection a plurality of times while the coin
passes between the coils. The control part compares the detection
signal from the detecting part and a reference signal stored in the
storage part so as to determine authentication and a denomination
of the coin.
Inventors: |
Miyauchi; Satoshi; (Gifu,
JP) ; Nara; Takehiko; (Osaka, JP) ; Ueki;
Tooru; (Osaka, JP) ; Ikeda; Kouji; (Aichi,
JP) |
Correspondence
Address: |
PEARNE & GORDON LLP
1801 EAST 9TH STREET, SUITE 1200
CLEVELAND
OH
44114-3108
US
|
Assignee: |
PANASONIC CORPORATION
Osaka
JP
|
Family ID: |
39606674 |
Appl. No.: |
12/303325 |
Filed: |
July 10, 2007 |
PCT Filed: |
July 10, 2007 |
PCT NO: |
PCT/JP2007/063708 |
371 Date: |
December 3, 2008 |
Current U.S.
Class: |
194/317 |
Current CPC
Class: |
G07D 5/08 20130101 |
Class at
Publication: |
194/317 |
International
Class: |
G07D 5/08 20060101
G07D005/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2006 |
JP |
2006-195252 |
Apr 18, 2007 |
JP |
2007-108898 |
Claims
1. A coin discriminating device comprising: a detecting part having
a first sensor including a pair of coils and an oscillating
circuit, the detecting part being supplied with voltage from a
power source, and configured to output a detection signal varied by
a coin passing between the pair of coils; a first switching part
configured to switch magnetic connection of the pair of coils a
plurality of times between an in-phase connection and a
reversed-phase connection while the coin passes between the pair of
coils; a storage part configured to store a reference signal; and a
control part configured to compare the detection signal and the
reference signal, thereby determine authentication and a
denomination of the coin.
2. The coin discriminating device according to claim 1, wherein the
first switching part has two pairs of switches, and one of the
switches is connected between the first sensor and the power
source.
3. The coin discriminating device according to claim 1, wherein the
detecting part further has a second sensor made up of a pair of
coils.
4. The coin discriminating device according to claim 3, further
comprising a second switching part configured to switch the
detection signal by the first sensor, and a detection signal by the
second sensor.
5. The coin discriminating device according to claim 4, wherein the
second switching part is provided between the power source, and the
first sensor and the second sensor.
6. The coin discriminating device according to claim 4, wherein the
second switching part is made up of a plurality of switching
elements.
7. The coin discriminating device according to claim 1, wherein the
detecting part further has a capacitor connected to the first
sensor.
8. The coin discriminating device according to claim 7, wherein the
capacitor is connected to the first sensor in series.
9. The coin discriminating device according to claim 1, wherein the
detecting part further has a plurality of capacitors, and the coin
discriminating device further comprises a third switching part
configured to switch the plurality of capacitors to be connected to
the first sensor.
10. The coin discriminating device according to claim 9, wherein
the third switching part is made up of a plurality of switching
elements.
11. The coin discriminating device according to claim 1, further
comprising an offset switching circuit configured to switch offset
voltages for offsetting the detection signal.
12. The coin discriminating device according to claim 1, wherein
the oscillating circuit is configured to switch frequencies to
oscillate.
13. The coin discriminating device according to claim 1, further
comprising a gain switching circuit configured to vary a gain of
the detecting part so as to switch a gain of the detection
signal.
14. The coin discriminating device according to claim 1, wherein
the oscillating circuit is a separately-excited oscillating circuit
that oscillates at a predetermined oscillation frequency regardless
of an inductance value of the first sensor.
15. The coin discriminating device according to claim 14, wherein
the oscillation frequency of the oscillating circuit is set based
on a tuning frequency before the coin passes between the pair of
coils.
16. The coin discriminating device according to claim 15, wherein
the oscillation frequency of the oscillating circuit when the pair
of coils are connected in phase is set to be away from the tuning
frequency before the coin passes between the pair of coils by a
predetermined frequency.
17. The coin discriminating device according to claim 15, wherein
the oscillation frequency of the oscillating circuit when the pair
of coils are connected in reversed phase is set to a substantially
identical frequency as the tuning frequency before the coin passes
between the pair of coils.
18. The coin discriminating device according to claim 14, wherein
the control part is configured to detect the tuning frequency
before the coin passes between the pair of coils and correct the
oscillation frequency of the oscillating circuit.
19. The coin discriminating device according to claim 18, wherein
the oscillating circuit includes a frequency divider that is
controlled by the control part and is configured to correct the
oscillation frequency of the oscillating circuit.
20. The coin discriminating device according to claim 1, wherein
the detecting part further has: a capacitor connected to the first
sensor and making up a tuning circuit together with the first
sensor; and an amplifying part connected to the tuning circuit, and
making up the oscillating circuit together with the tuning circuit,
and the oscillating circuit is a self-excited oscillating
circuit.
21. The coin discriminating device according to claim 1, further
comprising a shaping part configured to shape the detection signal
and output an envelope waveform to the control part.
22. The coin discriminating device according to claim 21, wherein
the shaping part has a peak-hold circuit and a reset circuit
configured to set the peak-hold circuit to an initial state.
23. The coin discriminating device according to claim 1, further
comprising a stabilizing part configured to stabilize the output
from detecting part to the control part.
24. The coin discriminating device according to claim 23, wherein
the stabilizing part is formed of a buffer circuit connected
between the detecting part and the control part.
25. The coin discriminating device according to claim 23, wherein
the stabilizing part is formed of an offset switching circuit
configured to speed up a rise of an oscillation amplitude of the
oscillating circuit by switching offset voltages for offsetting the
detection signal.
26. The coin discriminating device according to claim 1, wherein
the first switching part is formed of a plurality of switching
elements.
Description
[0001] This application is a U.S. national phase application of PCT
international application PCT/JP2007/063708.
TECHNICAL FIELD
[0002] The present invention relates to a coin discriminating
device mounted on a vending machine or the like.
BACKGROUND ART
[0003] FIG. 21 is a front perspective diagram showing a schematic
configuration of a conventional coin discriminating device. This
coin discriminating device has housing 1, slot 3, passage 4, three
sensors 5, 6 and 7, gate 8, return passage 9, sorting passage 10,
discriminating part 11, and storage cylinders 12. Slot 3 for
accepting coin 2 is provided at an upper part of housing 1, and
passage 4 is connected to slot 3 and is provided so as to be
inclined downward. Sensors 5, 6, 7 are provided on a side wall of
passage 4. Gate 8 is provided at an end of passage 4. Return
passage 9 is connected to one side of gate 8, and sorting passage
10 is connected to another side of gate 8. Coin 2 sorted by sorting
passage 10 is stored in one of storage cylinders 12. Outputs of
sensors 5, 6, 7 are supplied to discriminating part 11.
[0004] Operation of the coin discriminating device configured as
mentioned above is described below. Coin 2 dropped into slot 3
rolls on passage 4. Along the way, sensor 5 senses irregularity in
the surfaces of coin 2, sensor 6 senses a material of coin 2, and
sensor 7 senses a thickness of coin 2. Sensors 5, 6 and 7 transmit
sensed characteristics of coin 2 to discriminating part 11. Based
on these characteristics, discriminating part 11 discriminates
authentication and a denomination of coin 2. Based on the
discrimination result, a counterfeit coin is guided from gate 8 to
return passage 9. On the other hand, a real coin is guided from
gate 8 to sorting passage 10 to be stored in one of storage
cylinders 12 by denomination. The above-described coin
discriminating device is disclosed, for example, in Patent Document
1 by the inventors of the present application.
[0005] Thus, in the conventional coin discriminating device,
dedicated sensors 5, 6, 7 are attached independently in order to
obtain the characteristics of the irregularity, material and
thickness of coin 2. Sensors 5, 6, 7 are installed in order from an
upstream side of passage 4, and two of these cannot be installed in
the same place. Accordingly, the irregularity, material and
thickness of coin 2 are detected independently of each other in
different places without associating with each other. Therefore,
sensing a correlation between the irregularity, material and
thickness of coin 2 at the same site is difficult, and the precise
discrimination of coin 2 has limitations.
[0006] Patent Document 1: Unexamined Japanese Patent Publication
No. 2006-59139
SUMMARY OF THE INVENTION
[0007] The present invention is a coin discriminating device
capable of detecting also a correlation of two types of
characteristics at the same site of a coin. The coin discriminating
device of the present invention has a detecting part, a first
switching part, a storage part, and a control part. The detecting
part has a first sensor including a pair of coils, and an
oscillating circuit, is supplied with voltage from a power source,
and outputs a detection signal varied by passing of a coin between
the coils. The first switching part switches a magnetic connection
of the coils between an in-phase connection and a reversed-phase
connection a plurality of times while the coin passes between the
coils. The control part compares the detection signal from the
detecting part and a reference signal stored in the storage part so
as to determine authentication and a denomination of the coin.
Thus, since the first switching part switches the magnetic
connection of the coils between the in-phase connection and the
reversed-phase connection a plurality of times while the coin
passes between the coils, the correlation of the plurality types of
characteristics at the same site of the coin can be detected.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a front perspective view showing a schematic
configuration of a coin discriminating device in a first exemplary
embodiment of the present invention.
[0009] FIG. 2 is a block diagram for simplistically explaining a
configuration of a coin discriminating device in each of first to
fourth exemplary embodiments of the present invention.
[0010] FIG. 3 is a cross-sectional diagram showing a first state of
a first sensor making up the coin discriminating device shown in
FIG. 2.
[0011] FIG. 4 is a cross-sectional diagram showing a second state
of the first sensor shown in FIG. 3.
[0012] FIG. 5 is a circuit diagram showing a connection
configuration between a first switching part and the first sensor
shown in FIG. 2.
[0013] FIG. 6 is a circuit diagram showing a connection
configuration of a third switching part, the first sensor and a
capacitor group shown in FIG. 2.
[0014] FIG. 7 is an output waveform diagram outputted from the
first sensor and a second sensor of the coin discriminating device
shown in FIG. 2.
[0015] FIG. 8 is a diagram showing the respective waveforms shown
in FIG. 7 in an expanded manner, and showing output signal
waveforms of the respective parts.
[0016] FIG. 9 is a block diagram of the coin discriminating device
in the first exemplary embodiment of the present invention.
[0017] FIG. 10 is a circuit diagram of a tuning circuit, a
detecting circuit and vicinity thereof in FIG. 9.
[0018] FIG. 11 is a circuit diagram of an electronic switch, which
is one of switches in FIG. 10.
[0019] FIG. 12 is a tuning property diagram by difference in
material of a coin.
[0020] FIG. 13 is a tuning property diagram by difference in
thickness of the coin.
[0021] FIG. 14 is a cross-sectional diagram of a coin to be
discriminated in the second exemplary embodiment of the present
invention.
[0022] FIG. 15 is a property diagram showing variations of an
output voltage of a tuning circuit with respect to a depth from a
top surface of the coin shown in FIG. 14.
[0023] FIG. 16 is a circuit diagram showing a part of a tuning
circuit of the coin discriminating device in the third exemplary
embodiment of the present invention.
[0024] FIG. 17 is a block diagram of the coin discriminating device
in the fourth exemplary embodiment of the present invention.
[0025] FIG. 18 is a circuit diagram of an oscillating part in FIG.
17.
[0026] FIG. 19 is a diagram showing output waveforms outputted from
the first and second sensors of the coin discriminating device and
output signal waveforms of respective parts shown in FIG. 17.
[0027] FIG. 20 is a circuit diagram showing one example of a buffer
circuit applied to the first and fourth exemplary embodiments.
[0028] FIG. 21 is a front perspective view showing a schematic
configuration of a conventional coin discriminating device.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0029] Hereinafter, referring to the drawings, embodiments of the
present invention are described. In the respective embodiments,
parts similar to those in the preceding embodiment are given the
same reference marks, and description may be simplified.
First Exemplary Embodiment
[0030] FIG. 1 is a front perspective showing a schematic
configuration of coin discriminating device 21 in a first exemplary
embodiment of the present invention. Coin discriminating device 21
has housing 22, slot 23, passage 24, first sensor 25 (hereinafter,
sensor 25), second sensor 26 (hereinafter, sensor 26), gate 27,
return passage 28, sorting passage 29, and storage cylinders
30.
[0031] Slot 23 for accepting coin 20 is provided in an upper part
of housing 22, and is connected to passage 24 through snubber 24A.
Passage 24 is provided downward with an inclination of about 10 to
12 degrees. Sensors 25, 26 are attached to side walls of passage 24
in this order.
[0032] For example, the diameter of sensor 25 is 8.3 mm, and the
diameter of sensor 26 is 12.5 mm. Sensors 25, 26 are each attached
so that a distance from a bottom surface of passage 24 to a center
of the each sensor is, for example, 13.25 mm. Moreover, the centers
of sensors 25, 26 are separated, for example, by 25.0 mm.
[0033] Gate 27 is provided at an end of passage 24 to sort coin 20
in accordance with authenticity. Return passage 28 to which
counterfeit coins are guided is connected to one side of gate 27,
and sorting passage 29 to which real coins are guided is connected
to another side of gate 27. Storage cylinders 30 are connected to
sorting passage 29 to store coin 20 sorted by sorting passage 29 by
denomination.
[0034] Next, with reference to FIGS. 2 to 4, a description is
given, focusing on electric circuitry of coin discriminating device
21. FIG. 2 is a block diagram for simplistically explaining a
configuration of coin discriminating device 21. FIGS. 3 and 4 are
cross-sectional diagrams of sensors 25, 26.
[0035] As shown in FIG. 2, coin discriminating device 21 has
sensors 25, 26, oscillating circuit 90, capacitor groups 731, 732,
first switching part 91, second switching part 92 and third
switching part 93, shaping part 94, control part 95, and storage
part 49 as electric circuitry. Sensor 25 and capacitor group 731,
sensor 26 and capacitor group 732, and oscillating circuit 90 make
up detecting part 96. Storage part 49 in which a reference signal
is stored in advance is connected to control part 95. Control part
95 compares a detection signal inputted through shaping part 94
with the reference signal stored in storage part 49 so as to
determine the authenticity and the denomination of coin 20.
[0036] Next, with reference to FIGS. 3 and 4, sensors 25, 26 are
described. Sensor 25 is constructed by winding coils 42A, 42B
around ferritic cores 41A, 41B, which are attached so as to be
opposed to both walls of passage 24, respectively. Sensor 26 is
similarly constructed by winding coils 44A, 44B around ferritic
cores 43A, 43B, which are attached so as to be opposed to the both
walls of passage 24. Hereinafter, since sensors 25, 26 basically
have the same configuration, a description is given,
representatively focusing on sensor 25.
[0037] A magnetic connection of coil 42A and coil 42B is switched
between a series in-phase connection and a series reversed-phase
connection by first switching part 91. FIG. 3 shows lines of
magnetic force 50A when coil 42A and coil 42B are connected in
series and in phase. Lines of magnetic force 50A are outputted in a
direction where they penetrate coin 20 in passage 24, so that
mainly characteristics of a material of coin 20 are sensed
efficiently.
[0038] FIG. 4 shows lines of magnetic force 50B when coil 42A and
coil 42B are connected in series and in reversed phase. Lines of
magnetic force 50B are outputted in a direction where they are
limited by coin 20 in passage 24, so that mainly characteristics of
irregularity in the surfaces and thickness of coin 20 are sensed
efficiently.
[0039] That is, detecting part 96 having sensor 25 including the
pair of coils 42A, 42B and oscillating circuit 90 outputs a
detection signal that are varied by coin 20 passing between coils
42A, 42B. A principle for switching the above-described magnetic
connection of coil 42A and coil 42B between the series in-phase
connection and the series reversed-phase connection to acquire
different pieces of information of coin 20 will be described
later.
[0040] While coil 42A and coil 42B are connected in series, the
connection is not limited to the series connection, but it may be a
parallel connection, that is, may be switched between parallel
in-phase connection and parallel reversed-phased connection. The
series connection results in a large variation, which allows a
minute variation to be detected. In contrast, the parallel
connection allows a stable output to be sensed.
[0041] As described above, sensor 26 has a similar configuration to
that of sensor 25, and the diameter of sensor 26 is larger than
that of sensor 25. Therefore, by switching the in-phase connection
and the reversed-phase connection, sensor 25 can sense material
information and irregularity information of coin 20, and sensor 26
can sense material information and thickness information,
respectively.
[0042] Next, functions of first switching part 91, and third
switching part 93 are described. FIG. 5 is a circuit diagram
showing a connection configuration of sensor 25 made up of coils
42A, 42B, and switches 71A, 71B and 71J which make up first
switching part 91. When switch 71A is shunted and switch 71J is
connected to a downside of the figure, coils 42A and 42B are
brought into the series in-phase connection. On the other hand,
when switch 71B is shunted, and switch 71J is connected to an
upside of the figure, coils 42A, 42B are brought into the series
reversed-phase connection. In this manner, first switching part 91
switches the magnetic connection of coils 42A, 42B between the
series in-phase connection and the series reversed-phased
connection. Similarly, first switching part 91 switches the
connection of coils 44A, 44B in sensor 26 between the series
in-phase connection and the series reversed-phased connection,
respectively.
[0043] FIG. 6 is a circuit diagram showing a connection
configuration of sensor 25 made up of coils 42A, 42B, switches 71E,
71F making up third switching part 93, and capacitors 73A, 73B
included in capacitor group 731. For simplification, first
switching part 91 is not shown. Third switching part 93 switches
capacitors 73A, 73B to be connected to sensor 25. Capacitors 73A,
73B have different capacitances from each other, and are included
in capacitor group 731. Since capacitors 73A, 73B are provided
independently in this manner, a frequency adjustment for the series
in-phase connection and the series reversed-phase connection can be
performed easily. Similarly, capacitor group 732 includes two
capacitors independently, and third switching part 93 selects and
switches the capacitor in accordance with a case of series in-phase
connection and a case of series reversed-phase connection of coils
44A, 44B of sensor 26, by which the frequency adjustment is
performed. Thus, it is preferable that detecting part 96 has a
plurality of capacitors 73A, 73B different in capacitance, and that
third switching part 93 switches capacitors 73A, 73B to be
connected to sensor 25 or sensor 26. While capacitor groups 731,
732 are made up of the capacitors different in capacitance,
alternatively, in capacitor groups 731, 732, a plurality of
capacitors having the same capacitance may be used and be connected
in series and/or in parallel. That is, third switching part 93 only
needs to switch the capacitance connected to sensor 25, 26 to a
value suitable for the in-phase connection or the reversed-phase
connection, and configurations of capacitor groups 731, 732 are not
limited.
[0044] While third switching part 93 performs the frequency
adjustment by selecting and switching the capacitor in accordance
with the case of the series in-phase connection and the case of the
series reversed-phase connection of coils 44A, 44B of sensor 26,
third switching part 93 may vary a frequency by selecting and
switching the capacitor without changing the connection of coils
44A, 44B of sensor 26. That is, the frequency adjustment by third
switching part 93 is not limited to operation at the same time as
the switching between the in-phase connection and the
reversed-phase connection of coils 44A, 44B by first switching part
91. Only varying the frequency allows the plurality of different
types of coin characteristics to be detected.
[0045] Next, a function of second switching part 92 is described.
Second switching part 92 plays a role of switching the detection
signal outputted from detecting part 96 including sensors 25, 26 to
send to control part 95 through shaping part 94.
[0046] Next, one example of a discriminating method in coin
discriminating device 21 configured in this manner is described.
FIG. 7 shows envelope waveforms obtained by smoothing detected
outputs of sensors 25, 26 when coin 20 passes between coils 42A,
42B, and between coils 44A, 44B. Output waveform 52 is obtained
when coils 42A, 42B of sensor 25 are connected in series and in
phase, and output waveform 53 is obtained when coils 42A, 42B are
connected in series and in reversed phase. Output waveform 54 is
obtained when coils 44A, 44B of sensor 26 are connected in series
and in phase, and output waveform 55 is obtained when coils 44A,
44B are connected in series and in reversed phase.
[0047] In the present embodiment, first switching part 91 switches
the connection of coils 42A, 42B to the series in-phase connection
or to the series reversed-phase connection. At the same time, third
switching part 93 selects the connection of capacitor 73A to sensor
25 or the connection of capacitor 73B to sensor 25 and performs the
switching. Therefore, for example, series in-phase connection
waveform level 52A indicating the characteristics of the material
of coin 20 and series reversed-phase connection waveform level 53A
indicating the characteristics of the irregularity of coin 20 at
time 56A can be detected almost simultaneously.
[0048] Sensor 25 having a diameter of 8.3 mm and sensor 26 having a
diameter of 12.5 mm are arranged so that the centers thereof are
separated from each other by 25.0 mm. Accordingly, when coin 20
having a diameter of 14.60 mm or more flows between sensors 25, 26,
coin 20 is sensed by both sensors 25, 26. Accordingly, sensor 25
can detect series in-phase connection waveform level 52A and series
reversed-phase connection waveform level 53A, and sensor 26 can
also detect series in-phase connection waveform level 54A and
series reversed-phase connection waveform level 55A almost
simultaneously.
[0049] Switching operation in each of first switching part 91,
second switching part 92, and third switching part 93 is performed
by control part 95. Alternatively, a dedicated microcomputer that
performs switching control may be prepared separately, and first
switching part 91, second switching part 92 and third switching
part 93 may be switched at predetermined timing.
[0050] In this manner, in the present embodiment, first switching
part 91 switches coils 44A, 44B to the series in-phase connection
or to the series reversed-phase connection. Therefore, in sensor
26, series in-phase connection waveform level 54A indicating the
characteristics of the material of coin 20 and series
reversed-phase connection waveform level 55A indicating the
characteristics of the thickness of coin 20 at time 56A can also be
detected almost simultaneously.
[0051] Accordingly, at time 56A, the material information and the
irregularity information are sensed at the same point of coin 20
from waveform levels 52A and 53A of sensor 25. At the same time as
this sensing, the material information and the thickness
information of coin 20 are sensed at the same point of coin 20 from
waveform levels 54A, 55A of sensor 26. In this manner, mutual
information of sensor 25 and sensor 26 can be sensed. Accordingly,
coin 20 can be discriminated more precisely.
[0052] Next, with reference to FIG. 8, the switching by first
switching part 91 and information waveforms outputted from sensors
25, 26 by this switching are described. FIG. 8 shows the waveforms
shown in FIG. 7 in an expanded manner. A full span of a horizontal
axis indicates time of 1 msec. First switching part 91 divides this
1 msec into four time zones 61 to 64 of 250 .mu.sec. Second
switching part 92 switches outputs from sensors 25, 26 to shaping
part 94 in conjunction with first switching part 91. First
switching part 91 and second switching part 92 repeat a series of
operation in time zones 61 to 64, by which control part 95
continuously takes in the outputs of sensors 25, 26 through shaping
part 94 sequentially.
[0053] That is, in time zone 61, coils 42A, 42B of sensor 25 are
connected in series and in phase, so that the characteristics of
the material of coin 20 are mainly sensed. In time zone 62, coils
42A, 42B of sensor 25 are connected in series and in reversed
phase, so that the irregularity of coin 20 is mainly sensed.
[0054] In time zone 63, coils 44A, 44B of sensor 26 are connected
in series and in phase, so that the characteristics of the material
of coin 20 are mainly sensed. In time zone 64, coils 44A, 44B of
sensor 26 are connected in series and in reversed phase, so that
the thickness of coin 20 is mainly sensed.
[0055] As described above, control part 95 can receive two pieces
of information per sensor at the same point of coin 20 by an action
of first switching part 91. Thereby, a number of required types of
information can be acquired even if the sensors are reduced in
number, and uniformity in position where the information is
acquired is improved, so that discrimination precision is enhanced.
In a case where four types of information are acquired within 1
msec as described above, a speed at which coin 20 passes through
passage 24 is about 0.2 m/sec and thus, positions of coin 20 where
these types of information are acquired are within a range of 0.2
mm. Moreover, since shaping part 94 can be shared by providing
second switching part 92, a circuit configuration can be
simplified, contributing to cost reduction.
[0056] Next, an example of a specific circuit configuration and
operation thereof are described with reference to FIGS. 8 to 10.
FIG. 9 is a specific block diagram of coin discriminating device
21. FIG. 10 is a circuit diagram of tuning circuit 40, detecting
circuit 45 and vicinity thereof in FIG. 9.
[0057] In FIG. 9, crystal oscillating element 35 oscillates, for
example, at 8 MHz, and is connected to oscillator 37 inside
microcomputer 36. A clock signal is outputted from oscillator 37,
and this clock signal is connected to frequency divider 38 and
switching control part 39. That is, crystal oscillating element 35,
oscillator 37, and frequency divider 38 make up oscillating circuit
90 in FIG. 2. Oscillating circuit 90 is a separately-excited
oscillating circuit that separately oscillates tuning circuit 40
described later at a predetermined frequency regardless of
inductance values of sensors 25, 26.
[0058] An output of frequency divider 38 is connected to tuning
circuit 40 including sensors 25, 26. Coils 42A, 42B, 44A, 44B are
connected to capacitors 73A to 73D to make up tuning circuit 40.
That is, tuning circuit 40 and switching control part 39 make up
detecting part 96, first switching part 91 and second switching
part 92 in FIG. 2. The connection inside tuning circuit 40 is
electronically switched by an output of switching control part 39.
Moreover, a frequency division ratio of frequency divider 38 is
switched based on the output of switching control part 39.
[0059] An output of tuning circuit 40 is inputted to detecting
circuit 45. Detecting circuit 45 incorporates a wave-detecting
circuit, a peak-hold circuit, and a reset circuit that resets this
peak-hold circuit. The reset circuit in detecting circuit 45 is
reset by the output of switching control part 39. An output of
detecting circuit 45 is connected to discriminating circuit 47
through analog/digital converter (A/D converter) 46. The peak-hold
circuit and the reset circuit of detecting circuit 45, and A/D
converter 46 shape the detection signal from tuning circuit 40 to
output an envelope waveform to discriminating circuit 47. These
make up shaping part 94 in FIG. 2.
[0060] An output of discriminating circuit 47 is connected to
output terminal 48. Data indicating the authentication and the
denomination of dropped coin 20 is outputted from output terminal
48. That is, discriminating circuit 47 and switching control part
39 make up control part 39 in FIG. 2. Offset switching circuit 69
connected between frequency divider 38 and tuning circuit 40 will
be described later.
[0061] Next, referring again to FIG. 8, the respective outputs from
frequency divider 38, tuning circuit 40, switching control part 39,
and detecting circuit 45 and relations therebetween are described.
The frequency division ratio of frequency divider 38 is switched by
switching control part 39. Frequency divider 38 outputs signals 61A
to 64A of different frequencies. In time zone 61, frequency divider
38 switches the frequency division ratio so that signal 61A of 100
kHz is outputted to coils 42A, 42B, for example.
[0062] Similarly, in time zone 62, frequency divider 38 switches
the frequency division ratio to output signal 62A of 120 kHz, for
example, to coils 42A, 42B. In time zone 63, frequency divider 38
switches the frequency division ratio to output signal 63A of 170
kHz, for example, to coils 44A, 44B, and in time zone 64, outputs
signal 64A of 215 kHz, for example, to coils 44A, 44B.
[0063] Upon receiving signals 61A to 64A, tuning circuit 40 outputs
signals 61B to 64B in time zones 61 to 64, respectively. As shown
in the figure, it takes about 100 .mu.sec for the operation of
tuning circuit 40 to become stable, and for the output to become
substantially constant.
[0064] Switching control part 39 outputs reset signals 61C to 64C
of 50 .mu.sec at an end of each of time zones 61 to 64. Based on
these reset signals, the peak-hold circuit in detecting circuit 45
is reset.
[0065] Detecting circuit 45 detects signals 61B to 64B outputted
from tuning circuit 40 to peak-hold the same, and outputs signals
61D to 64D. Detecting circuit 45, having the reset circuit,
performs reset using reset signals 61C to 64C at the end of each of
time zones 61 to 64 to prevent influence of a previous time of
being exerted. A/D converter 46 converts signal 61D to 64D to
digital amounts and supplies them to discriminating circuit 47.
[0066] Time when coin 20 passes through sensors 25, 26 is about 100
msec, respectively. Accordingly, each of sensors 25, 26
sequentially extracts the characteristics at 100 different points
for one coin 20. In the present embodiment, the switching between
the in-phase connection and the reversed phase connection, and the
switching between sensors 25, 26 are performed by switching control
part 39 so that 400 pieces of characteristic data are acquired
within 100 msec. That is, switching is performed 400 times by
switching control part 39 (100 points.times.2.times.2). Thus, since
switching control part 39 performs the switching frequently,
discriminating circuit 47 can acquire the characteristic data
necessary for discrimination of coin 20 without adjusting timing
when coin 20 is dropped and reaches sensors 25, 26. That is,
switching control part 39 and discriminating circuit 47 need not be
in conjunction with each other.
[0067] In the present embodiment, the irregularity and the material
of coin 20 are sensed by sensor 25, and the thickness and the
material of coin 20 are sensed by sensor 26 to precisely
discriminate coin 20. However, even only one sensor allows the
irregularity or thickness and material of coin 20 to be
discriminated by switching this sensor between the in-phase
connection and the reversed-phase connection. Hereinafter, a number
of times of switching required when one sensor is used is
described.
[0068] If the switching by switching control part 39 is slow, the
precise characteristics of coin 20 cannot be sensed. With at least
one sensor, the characteristics of coin 20 at 5 or more different
points need to be acquired. Furthermore, considering the switching
between the in-phase connection and the reversed-phase connection,
10 or more times of switching within the passage time of coin 20
are required. Moreover, the faster the switching by switching
control part 39 is, the more precise sensing information can be
acquired. However, making the switching faster than needed will
place a burden to microcomputer 36. In view of the foregoing, it is
preferable that the switching of switching control part 39 is set
to 10 to 1000 times with one sensor.
[0069] Next, with reference to FIG. 10, more specific circuit
configuration is described. Tuning circuit 40 is connected between
a collector of transistor 66 and power source 70. Input terminal 65
is connected to the output of frequency divider 38, and is
connected to a base of transistor 66 through resistor 67A. Resistor
67B is connected between the base of transistor 66 and a ground,
and offset switching circuit 69 is connected to an emitter of
transistor 66. The output of tuning circuit 40 is inputted to
detecting circuit 45 through terminal 72.
[0070] Next, tuning circuit 40 is described. A first terminal of
each of switches 71A to 71D is connected to power source 70. A
second terminal of switch 71A is connected to a first terminal of
switch 71E, a first selection terminal of switch 71J, and a second
terminal of coil 42A. A common terminal of switch 71J is connected
to a second terminal of coil 42B, and a first terminal of the coil
42B is connected to terminal 72 which is connected to the collector
of transistor 66. Moreover, a second terminal of switch 71E is
connected to terminal 72 through capacitor 73A.
[0071] A second terminal of switch 71B is connected to a first
terminal of coil 42A, a second selection terminal of switch 71J,
and a first terminal of switch 71F. A second terminal of switch 71F
is connected to terminal 72 through capacitor 73B.
[0072] A second terminal of switch 71C is connected to a first
terminal of switch 71G, a first selection terminal of switch 71K,
and a second terminal of coil 44A. A common terminal of switch 71K
is connected to a second terminal of coil 44B, and a first terminal
of coil 44B is connected to terminal 72. Moreover, a second
terminal of switch 71G is connected to terminal 72 through
capacitor 73C.
[0073] A second terminal of switch 71D is connected to a first
terminal of coil 44A, a second selection terminal of switch 71K and
a first terminal of switch 71H. Moreover, a second terminal of
switch 71H is connected to terminal 72 through capacitor 73D.
[0074] Switches 71A to 71D, switches 71E to 71H, and switches 71J,
71K are sequentially switched by switching control part 39 in
accordance with time zones 61 to 64 shown in FIG. 8. More
specifically, in time zone 61, switch 71A and switch 71E are
shunted, and switch 71J is switched to the second selection
terminal side. This allows coil 42A and coil 42B to be connected in
series and in phase. Capacitor 73A is connected in parallel to a
series connected unit of coil 42A and coil 42B.
[0075] In time zone 62, switch 71B and switch 71F are shunted, and
switch 71J is switched to the first selection terminal side. This
allows coil 42A and coil 42B to be connected in series and in
reversed phase. Capacitor 73B is connected in parallel to a series
connected unit of coil 42A and coil 42B.
[0076] In time zone 63, switch 71C and switch 71G are shunted, and
switch 71K is switched to the second selection terminal side. This
allows coil 44A and coil 44B to be connected in series and in
phase. Capacitor 73C is connected in parallel to a series connected
unit of coil 44A and coil 44B.
[0077] In time zone 64, switch 71D and switch 71H are shunted, and
switch 71K is switched to the first selection terminal side. This
allows coil 44A and coil 44B to be connected in series and in
reversed phase. Capacitor 73D is connected in parallel to a series
connected unit of coil 44A and coil 44B.
[0078] In switches 71A to 71D, only one selected switch is turned
on, and the other switches are turned off as well as in switches
71E to 71H. In this manner, switches 71A, 71B, 71J make up first
switching part 91 for sensor 25 in FIG. 2. Switches 71C, 71D, 71K
make up first switching part 91 for sensor 26 in FIG. 2. Switches
71E, 71F make up third switching part 93 for sensor 25, and
switches 71G, 71H make up third switching part 93 for sensor
26.
[0079] Moreover, switching control part 39 switches sensor 25 and
sensor 26 with respect to detecting circuit 45 within 1 msec. That
is, switches 71A, 71B, 71C, 71D make up second switching part 92 in
FIG. 2.
[0080] The first terminal of each of switches 71A to 71D is
directly connected to power source 70. That is, first switching
part 91 has a pair of switches 71A, 71B and switch 71J for sensor
250. The pair of switches 71A, 71B is connected between sensor 25
and power source 70. Thereby, first switching part 91 can perform
switching without exerting a harmful influence of high frequency on
tuning circuit 40. From a different view point, second switching
part 92 is provided between power source 70 and sensors 25, 26.
Thereby, second switching part 92 can also perform switching
without exerting a harmful influence of high frequency on tuning
circuit 40.
[0081] In the circuit diagram of FIG. 10, the connection between
power source 70 and coils 42A, 44A is switched by switches 71A to
71D provided outside the parallel circuit made up of coils and
capacitors. In a parallel circuit of coils 42A, 42B and either of
capacitors 73A, 73B, a pair of switch 71E, 71F and switch 71J are
provided. On the other hand, in a parallel circuit of coils 44A,
44B and either of capacitors 73C, 73D, a pair of switches 71G, 71H,
and switch 71K are provided. Such a simple configuration enables
switching including capacitors 73A to 73D, and the functions of
first switching part 91 and second switching part 92 to be
realized. A smaller resistance value included in each of the
parallel circuits made up of the coils and one of the capacitors is
more preferable. Therefore, it is preferable that in this manner,
the number of switches is made small to make up the circuit.
[0082] Moreover, since capacitors 73A to 73D forming tuning circuit
40 are provided independently of each other, frequency adjustment
of the series in-phase connection and that of the series
reversed-phase connection can be performed easily.
[0083] The output of tuning circuit 40 is outputted to terminal 72
and is inputted to detecting circuit 45. The output of detecting
circuit 45 is outputted from terminal 80 to A/D converter 46.
Detecting circuit 45 is made up of peak-hold circuit 74, reset
circuit 75, input terminal 76, and gain switching circuit 77.
Peak-hold circuit 74 is connected to terminal 72, and includes a
publicly known detector circuit. Reset circuit 75 resets peak-hold
circuit 74. Through input terminal 76, the reset signal is inputted
from switching control part 39 to reset circuit 75. Gain switching
circuit 77 is provided between an output end of peak-hold circuit
74 and terminal 80.
[0084] Gain switching circuit 77 is made up of resistors 78A to 78D
connected in series between an input and an output of operational
amplifier 77A, and switches 79A to 79D connected to resistors 78A
to 78D in parallel, respectively. Switching parts 79A to 79D are
switched by switching control part 39 corresponding to the
respective time zones 61 to 64 shown in FIG. 8. Gain switching
circuit 77 switches ON and OFF of switches 79A to 79D so as to
maximize a variation width of a gain in each of the outputs of
sensors 25, 26. This increases an S/N ratio of each of signals 61D
to 64D so as to enhance measurement precision.
[0085] Gain switching circuit 77 shown in FIG. 10 is made up of
resistors 78A to 78D, and switches 79A to 79D connected to
resistors 78A to 78D in parallel, respectively. Alternatively,
resistors 78A to 78D may be connected in parallel, and switches 79A
to 79D may be connected to resistors 78A to 78D in series
respectively to make up gain switching circuit 77.
[0086] Next, offset switching circuit 69 is described. Offset
switching circuit 69 is made up of resistors 67C, 67D, 67E, 67F,
67G, and switches 68A to 68D. Resistors 67C, 67D, 67E, 67F, 67G are
connected between the emitter of transistor 66 and a ground in
series. Each of switches 68A to 68D is connected to both ends of
each of resistors 67D to 67G. Switches 68A to 68D are switched by
switching control part 39 in accordance with time zones 61 to 64
shown in FIG. 8, and give an offset voltage determined in advance
for each of the above-described switching to an output voltage of
detecting circuit 45. That is, offset switching circuit 69 controls
the offset voltage by switching switches 68A to 68D so as to
increase an output voltage variation width of detecting circuit 45.
This increases the S/N ratio of each of signal 61D to 64D, and
enhances measurement precision.
[0087] In offset switching circuit 69 shown in FIG. 10, resistors
67D to 67G are connected in series, and respective resistors 67D to
67G and respective switches 68A to 68D are connected in parallel.
Alternatively, resistors 67D to 67G are connected in parallel, and
respective resistors 67D to 67G may be connected to respective
switches 68A to 68D in series. Moreover, zener diodes different in
zener voltage may be inserted into an input of peak-hold circuit 74
in parallel, and these zener diodes may be switched by an
electronic switch to thereby switch the offset voltage.
[0088] As described above, it is important for performing precise
measurement to maximize the variation width of the gain in each of
the outputs of sensors 25, 26 by gain switching circuit 77 and
offset switching circuit 69.
[0089] Next, a preferable configuration of each of switches 71A to
71K is described. FIG. 11 is a circuit diagram showing either of
switches 71A to 71K used in the present embodiment. Particularly,
for each of switches 71E to 71K used in tuning circuit 40, it is
preferable to use an electronic switch in a form using field-effect
transistors (FET). That is, it is preferable that each of first
switching part 91 and second switching part 92 is made up of a
plurality of FETs that are switching elements. This is to enhance
isolation of tuning circuit 40 in switching the frequency. This
configuration can also be used for switches 68A to 68D and switches
79A to 79D.
[0090] A signal controlled by switching control part 39 is inputted
to input terminal 81. Resistor 83A is connected between input
terminal 81 and a base of transistor 82. Resistor 83B is connected
between the base of transistor 82 and a ground. An emitter of
transistor 82 is directly connected to a ground, and a collector is
connected to power source 84 of 24 V, for example, through resistor
83C.
[0091] Moreover, the collector of transistor 82 is connected to a
gate of N channel FET 85A through resistor 83D. The collector of
transistor 82 is also connected to a gate of N channel FET 85B
through resistor 83E. A drain of FET 85A is connected to first
terminal 86A, and a source of FET 85A is connected to a source of
FET 85B. A drain of FET 85B is connected to second terminal
86B.
[0092] In this manner, two FETs 85A, 85B are connected in series.
This enhances isolation between terminals 86A, 86B, and improves
high-frequency performance. Moreover, since each of switches 71E to
71K is made up of FET 85A, 85B, an on-resistance can be made
extremely small. Each of switches 71J, 71K in tuning circuit 40
only needs to have two electronic switches shown in FIG. 11.
[0093] Next, a principle to acquire different pieces of information
of coin 20 by switching the magnetic connection of two opposed
coils 44A, 44B in sensor 26 is described. FIG. 12 shows output
properties of tuning circuit 40 when coils 44A and 44B are
connected in series and in phase, and coins 20 having the same
thickness but different materials are dropped, that is, it shows
variations in output voltage with respect to frequency.
[0094] Characteristic curve 103 is outputted at the time of no
loading when no metal exists in the vicinity of coils 44A, 44B. A
center frequency thereof is about 150 kHz. Characteristic curves
104 to 107 are outputted at the time of loading when metal exists
in the vicinity of coils 44A, 44B. A central frequency thereof is
about 170 kHz. Characteristic curve 104 shows a property in a case
where copper is used as loading metal making coin 20, and
characteristic curve 105 shows a property in a case where brass is
used as loading metal. Characteristic curve 106 shows a property in
a case where white copper is used as loading metal, and
characteristic curve 107 shows a property in a case nickel is used
as loading metal. As shown in the figure, the characteristic curves
show levels characterized by metallic species as the loading.
Accordingly, the material of dropped coin 20 can be sensed using
these characteristics of the level.
[0095] The center frequency of tuning circuit 40 is higher by about
20 kHz at the time of loading as compared with that at the time of
no loading. Accordingly, if an output frequency outputted from
frequency divider 38 is set to be higher by 20 kHz as compared with
the center frequency at the time of no loading, the material of
coin 20 can be sensed with a high sensitivity. Moreover, by setting
this setting frequency to be slightly higher than a peak frequency
at the time of loading, stability becomes favorable. That is, it is
preferable that an oscillation frequency of oscillating circuit 90
when coils 44A, 44B are connected in phase is set to be away by a
predetermined frequency (e.g., 20 kHz) from a tuning frequency
before coin 20 passes between coils 44A, 44B.
[0096] A peak frequency at the time of no loading is detected by
switching control part 39 (control part 95) measuring the output of
A/D converter 46 while varying the frequency by varying the
frequency division ratio of frequency divider 38. This detected
value is stored in storage part 49 in microcomputer 36. Frequency
divider 38 switches the frequency division ratio so that the
frequency stored in storage part 49 is set when coin 20 is not
dropped to thereby correct the oscillation frequency. Since in this
manner, variation with time and variation in temperature are
corrected, coin 20 can be precisely discriminated even when
circumstances are changed.
[0097] Moreover, by detecting the peak frequency at the time of no
loading is detected for each product at production time and storing
the same in storage part 49 of each of the product, the output
frequency of oscillator 37 can be optimized. Therefore, high
discrimination performance that is not affected by variations in
respective products can be achieved.
[0098] Moreover, while after shipment, switching control part 39
(control part 95) also detects the peak frequency when coin 20 is
not dropped, this measurement range can be limited to a relatively
narrow range (narrower range than that at the production time)
centering around the peak frequency stored for each of the product
at the production time. This can shorten a detection time of the
peak frequency.
[0099] FIG. 13 shows output properties of tuning circuit 40 when
coils 44A, 44B are connected in series and in reversed phase, and
coins 20 made of the same material and having different thicknesses
are dropped. Characteristic curve 113 is outputted at the time of
no loading when no metal exists in the vicinity of coils 44A, 44B.
Moreover, characteristic curves 114 to 120 are outputted at the
time of loading when metal exists in the vicinity of coils 44A,
44B. In either case, a central frequency is about 215 kHz. In
characteristic curve 114 at the time of loading, there arises a
loss caused by an eddy current of about 0.8 V, as compared with
characteristic curve 113 at the time of no loading. This decreases
a voltage level. Moreover, as shown in characteristic curves 114 to
120, a magnitude of the loss differs depending on the thickness of
the metal. That is, as the thickness increases from characteristic
curve 114 of a thin metal, changes from characteristic curves 115
to 120 are exhibited. Accordingly, these characteristics of the
level can be used to sense the thickness of dropped coin 20.
Therefore, it is preferable that the oscillation frequency when
coils 44A, 44B are connected in reversed phase is set to
substantially the same frequency as a tuning frequency before coin
20 passes between coils 44A, 44B.
[0100] With the setting of this frequency, an optimal frequency for
each product is set. Moreover, while in FIGS. 12 and 13, sensor 26
is described, a similar principle is applied to sensor 25. However,
since sensor 25 has a smaller diameter than sensor 26, lines of
magnetic force 50B in FIG. 4 do not spread in a surface direction
of coin 20. Therefore, when coils 42A, 42B are connected in
reversed phase, information in which irregularity of a relatively
minute area on a surface of coin 20 is reflected can be
acquired.
[0101] As described above, in coin discriminating device 21, the
output of oscillator 37 is supplied to tuning circuit 40 through
frequency divider 38, and oscillator 37 is provided independently
of tuning circuit 40. Thus, even if impedances of coils 42A, 42B,
44A, 44B are varied by an influence of coin 20, or an environmental
influence such as ambient temperature, the oscillation frequency of
oscillator 37 is not affected, so that coin 20 can be discriminated
stably.
Second Exemplary Embodiment
[0102] In the first exemplary embodiment, the principle for
discriminating the material of coin 20 made of a single material is
described. In the present embodiment, a principle for
discriminating materials of coin 20A made of a clad material of two
or more species of metal, and a corresponding configuration are
described.
[0103] FIG. 14 is a cross-sectional diagram of coin 20A constructed
as described above. For example, surface material 131 is white
copper, and core material 132 is copper. That is, coin 20A is, for
example, 10, 25, and 50 cents of United States.
[0104] As shown in FIG. 12, output properties of tuning circuit 40
vary depending on the coin material. While differences in output
property in a case of the same material and the different coin
thicknesses are shown in FIG. 13, in a case of the different coin
materials, the output voltage also differs. This difference in
output voltage can be utilized to discriminate surface material 131
from core material 132.
[0105] FIG. 15 is a property diagram showing variations in output
voltage of tuning circuit 40 with respect to a depth from a top
surface of coin 20A shown in FIG. 14. Characteristic curve 133
shows a case where a signal of an oscillation frequency higher than
that of characteristic curve 134 is inputted to tuning circuit 40.
At this time, coils 44A, 44B are connected in reversed phase.
[0106] When created AC magnetic fields of coil 44A, 44B permeate
coin 20A in a thickness direction thereof, a permeation depth
differs depending on the frequency. More specifically, in high
frequencies, the magnetic fields do not permeate deeply due to skin
effects, so that an influence of surface material 131 is large.
While in low frequencies, the magnetic fields permeate deeply, so
that surface material 131 and core material 132 affect the output
voltage level. Accordingly, based on a difference in output level
by surface material 131 and core material 132, coin 20A can be
discriminated.
[0107] More specifically, in FIG. 10, two types of different
frequencies switched by switching control part 39 are alternately
inputted from frequency divider 38 to input terminal 65. If the
material of surface material 131 and the material of core material
132 making up coin 20A are different, the output levels in tuning
circuit 40 in these inputted frequencies differ. Therefore, for
example, a difference in output voltage between at the time of no
loading and at the time of loading when a signal of 100 kHz is
inputted from input terminal 65 and a difference in output voltage
between at the time of no loading and at the time loading when a
signal of 200 kHz is inputted are detected. Values obtained in a
case of known coin 20A are stored in storage part 49 in advance,
and the detected differences are compared with the stored values by
discriminating circuit 47 (control part 95). This allows the
materials of coin 20A to be discriminated. In this manner, using
one sensor 26, the materials of coin 20A can be sensed by switching
the applied frequency.
Third Exemplary Embodiment
[0108] FIG. 16 is a circuit diagram showing a part of a tuning
circuit in the present embodiment. In the first exemplary
embodiment, sensors 25, 26 and capacitors 73A to 73D are connected
in parallel in tuning circuit 40. In the present embodiment,
sensors 25, 26, and capacitors 156 and 158 are connected in
parallel to make up the tuning circuit. More specifically, the
present exemplary embodiment is different from the first exemplary
embodiment in that the series tuning circuit is used, and the
tuning circuit in which circuit 151 and a circuit having a similar
configuration to that of circuit 151 are connected in series is
used in place of tuning circuit 40 in FIG. 10. Circuit 151 shows
only a part including sensor 25.
[0109] Circuit 151 is inserted between the collector of transistor
66 and terminal 72 of detecting circuit 45 in FIG. 10. In this
case, since this is a series tuning circuit, coupling capacitor 72A
connected to terminal 72 of detecting circuit 45 can be
omitted.
[0110] Hereinafter, a configuration of circuit 151 is described.
First terminal 152 of circuit 151 is connected to the first
terminal of coil 42A, and the second terminal of coil 42A is
connected to a common terminal of switch 154A. A first selection
terminal of switch 154A is connected to the first terminal of coil
42B, and the second terminal of coil 42B is connected to a first
selection terminal of switch 154B through capacitor 156. Moreover,
a common terminal of switch 154B is connected to second terminal
157 of circuit 151. A second selection terminal of switch 154A is
connected to the second terminal of coil 42B, and the first
terminal of coil 42B is connected to a second selection terminal of
switch 154B through capacitor 158.
[0111] Switches 154A, 154B are configured similarly to switches
71J, 71K of the first exemplary embodiment. Moreover, capacitors
156, 158 forming circuit 151 are provided independently of each
other. This allows frequency adjustment of the series in-phase
connection and that of the series reversed-phase connection to be
performed easily.
[0112] Operation of circuit 151 configured as above is described.
Switches 154A, 154B are switched in a direction indicated by a
solid line by the output of switching control part 39 in FIG. 9.
Thus, coils 42A, 42B are connected in series and in phase, and
capacitor 156 is connected in series to this series connected unit.
Since coils 42A, 42B are connected in series and in phase, the
material of coin 20 can be sensed efficiently.
[0113] Moreover, when switches 154A, 154B are switched in a
direction indicated by a dashed line by the output of switching
control part 39, coils 42A, 42B are connected in series and in
reversed phase. Simultaneously, capacitor 158 is connected in
series to this series connected unit. Since coils 42A, 42B are
connected in series and in reversed phase, the thickness of coin 20
can be sensed efficiently.
[0114] Since circuit 151 is a series tuning circuit, a Q value,
which is a value indicating a degree of resonance sharpness of a
resonance circuit, is large. The Q value in the series tuning
circuit is expressed by an inverse value of a product of R, .omega.
and C, where R is an internal resistance included in the tuning
circuit, C is a capacitance, and .omega. is an angular frequency.
Moreover, a use of circuit 151 allows first switching part 91 or
third switching part 93 in FIG. 2 to be made up of only switches
154A, 154B.
Fourth Exemplary Embodiment
[0115] FIG. 17 is a block diagram focusing on electric circuitry of
coin discriminating device 201 in a fourth exemplary embodiment.
FIG. 18 is a circuit diagram of oscillating part 204 in FIG. 17.
While a basic configuration is similar to that of FIG. 2 in the
first exemplary embodiment, a configuration of oscillating circuit
90 is different in the present embodiment. More specifically, in
the first exemplary embodiment, the output of oscillator 37 that
oscillates at a fixed frequency is supplied to tuning circuit 40
through frequency divider 38. In contrast, a self-excited
oscillating circuit including tuning circuit 202 of a variable
tuning frequency is used in the present embodiment.
[0116] As is evident from comparison between FIGS. 17 and 9, in
this configuration, switching control part 205 and oscillating part
204 are provided in place of switching control part 39, tuning
circuit 40, crystal oscillating element 35, oscillator 37, and
frequency divider 38. Switching control part 205 corresponds to
switching control part 39, and switches the connections in
oscillating part 204, and switches a gain of detecting circuit 45.
An output of oscillating part 204 is connected to detecting circuit
45. Switching control part 205, A/D converter 46, and
discriminating circuit 47 are configured by microcomputer 206, and
data indicating authentication and a denomination of dropped coin
20 is outputted from output terminal 48. That is, in this
configuration, oscillating part 204 serves as detecting part 96 in
FIG. 2.
[0117] As shown in FIG. 18, oscillating part 204 is made up of
tuning circuit 202 and amplifying part 203 for oscillation. Tuning
circuit 202 is formed of sensors 25, 26, and capacitors 221A, 221B,
222A to 222D connected in parallel to sensors 25, 26. That is,
oscillating part 204 performs self-exited oscillation. Details of
oscillating part 204 will be described later.
[0118] Next, referring to FIG. 19, switching by switching control
part 205, and waveforms of signals outputted from sensors 25, 26 by
this switching are described. Switching control part 205 divides 1
msec into four time zones 231, 232, 233, 234 at even intervals.
Switching control part 205 repeats a series of time of time zones
231 to 234, by which detecting circuit 45 continuously takes in the
outputs of sensors 25, 26 sequentially.
[0119] In time zone 231, coils 42A, 42B of sensor 25 are connected
in series and in phase, so that the characteristics of the material
of coin 20 are mainly sensed. In time zone 232, coils 42A, 42B of
sensor 25 are connected in series and in reversed phase, so that
the irregularity in the surfaces of coin 20 is mainly sensed.
[0120] In time zone 233, coils 44A, 44B of sensor 26 are connected
in series and in phase, so that the characteristics of the material
of coin 20 are mainly sensed. In time zone 234, coils 44A, 44B of
sensor 26 are connected in series and in reversed phase, so that
the thickness of coin 20 is mainly sensed.
[0121] Switching control part 205 outputs reset signals 231A to
234A of 50 .mu.sec at an end of each of time zones 231 to 234. As
shown in FIG. 18, reset circuit 216 is provided in amplifying part
203. Moreover, as described in the first exemplary embodiment,
peak-hold circuit 74 is provided in detecting circuit 45. Switching
control part 205 resets reset circuit 216 and peak-hold circuit 74
by reset signals 231A to 234A.
[0122] Oscillating part 204 outputs signals 231B to 234B in each of
time zones 231 to 234. It takes about 100 .mu.sec for the output of
oscillating part 204 to be stable and substantially constant.
Oscillating part 204 is reset by reset circuit 216 at the end of
each of time zones 231 to 234 to prevent influence on the
subsequent time.
[0123] The time until the output of oscillating part 204 becomes
stable can be shortened by using a stabilizing part. If the time
until the output of oscillating part 204 becomes stable is
shortened, the in-phase connection and the reversed-phase
connection of sensors 25, 26 can be switched more frequently, so
that the uniformity in measurement position can be further
improved.
[0124] As a specific example of the stabilizing part, it can be
realized by providing a buffer circuit using an operational
amplifier between output terminal 215 of tuning circuit 202 and
detecting circuit 45. FIG. 20 is a circuit diagram showing one
example of the buffer circuit. Output terminal 215 is connected to
a plus input terminal of operational amplifier 241 through
capacitor 243 and resistor 242. Moreover, a minus input terminal of
operational amplifier 241 is connected to an output side of
operational amplifier 241. Such a voltage follower 244 can be used
as the buffer circuit. Such a buffer circuit may be used in the
first exemplary embodiment. That is, voltage follower 244 may be
inserted between connection terminal 72 and detecting circuit
45.
[0125] As another example of the stabilizing part, offset switching
circuit 69 in FIG. 10 can be used. That is, offset switching
circuit 69 is controlled by switching control part 205 so that an
offset voltage is controlled only for first 50 .mu.sec in each
switching interval of 250 .mu.sec to speed up a rise of the
oscillation. More specifically, control over switches 68A to 68D of
offset switching circuit 69 by switching control part 205 allows
the stabilizing part to be realized. This control may be used in
the first exemplary embodiment. That is, switches 68A to 68D may be
controlled by switching control part 39 as described above.
[0126] Detecting circuit 45 detects signals 231B to 234B that
oscillating part 204 outputs in respective time zones 231 to 234
and applies the peak hold to the same so as to output signals 231C
to 234C. A detailed description of actions of detecting circuit 45
and the later, which are similar to those in the first exemplary
embodiment, is not given.
[0127] Next, with reference to FIG. 18, a circuit configuration of
oscillating part 204 is described. Oscillating part 204 has tuning
circuit 202 and amplifying part 203 in positive feedback connection
to tuning circuit 202.
[0128] First, amplifying part 203 is described. Input terminal 210
of amplifying part 203 is connected to minus input terminal 211A of
comparator 211. Resistor 212A is connected between minus input
terminal 211A and plus input terminal 211B. Resistors 212B and 212C
are connected in series between power source 70 and a ground. A
connection point thereof is connected to plus input terminal 211B
so as to supply a reference voltage to plus input terminal 211B of
comparator 211. Capacitor 213 is connected between plus input
terminal 211B and the ground.
[0129] Feedback resistor 212D is connected between output terminal
211C and minus input terminal 211A of comparator 211, and pull-up
resistor 212E is connected between output terminal 211C and power
source 70. Moreover, resistor 212F is connected between output
terminal 211C of comparator 211 and a base of NPN type transistor
214. Resistor 212J is connected between the base of transistor 214
and the ground. Resistors 212G and 212H are connected in series
between an emitter of transistor 214 and the ground.
[0130] Resistor 212G is used for offset voltage adjustment, and an
appropriate offset voltage is set by resistor 212G. In place of
resistor 212G, offset switching circuit 69 shown in the first
exemplary embodiment may be used.
[0131] A collector of transistor 214 is connected to terminal 72
and output terminal 215 of oscillating part 204. Moreover, reset
circuit 216 is connected to a connection point between the base of
transistor 214 and resistor 212F. In reset circuit 216, resistor
216C is connected between input terminal 216A and a base of NPN
type transistor 216B, and resistor 216D is connected between the
base of transistor 216B and the ground.
[0132] An emitter of transistor 216B is connected to the ground and
a collector thereof is connected to the connection point between
the base of transistor 214 and resistor 212F. Moreover, input
terminal 216A of reset circuit 216 is connected to switching
control part 205, and reset circuit 216 is reset at input timing of
each of reset signals 213A to 234A. Accordingly, at this timing,
the output of oscillating part 204 is stopped.
[0133] Next, tuning circuit 202 is described. Tuning circuit 202 is
connected between terminal 72 and input terminal 210 and determines
an oscillation frequency of oscillating part 204. Tuning circuit
202 is an almost similar circuit to tuning circuit 40 described in
the first exemplary embodiment, and a description is given,
focusing on differences.
[0134] In tuning circuit 202, capacitors 221A, 221B are connected
in series between power source 70 and terminal 72. A connection
point between capacitor 221A and capacitor 221B is connected to
input terminal 210 of amplifying part 203. In this configuration,
tuning circuit 202 is connected between an input of comparator 211
and the collector (output) of transistor 214 which make up
amplifying part 203, thereby oscillating part 204 performs the
self-excited oscillation.
[0135] Moreover, capacitor 222A is connected between the second
terminal of switch 71E and terminal 72. Similarly, capacitor 222B
is connected between the second terminal of switch 71F and terminal
72, and capacitor 222C is connected between the second terminal of
switch 71G and terminal 72. Moreover, capacitor 222D is connected
between the second terminal of switch 71H and terminal 72.
Capacitors 222A to 222D correspond to capacitors 73A to 73D in the
first exemplary embodiment, respectively.
[0136] A series unit of capacitors 221A, 221B is connected between
power source 70 and terminal 72 in parallel. In order to correct a
combined capacitance by addition of this series unit, capacitance
values of capacitors 222A to 222D are smaller than those of
capacitors 73A to 73D in the first exemplary embodiment.
Accordingly, a tuning frequency is almost similar to that of tuning
circuit 40 in the first exemplary embodiment.
[0137] Moreover, switching of switches 71A to 71K is performed by
switching control part 205. This switching timing is similar to
that of switching control part 39 described in the first exemplary
embodiment.
[0138] As described above, switching control part 205 that switches
the signal outputted from oscillating part 204 within a period of
time when coin 20 passes through sensors 25, 26 a plurality of
times is also provided in the present embodiment. Since switching
control part 205 switches the signal outputted from oscillating
part 204 at a high speed while coin 20 passes through sensors 25,
26, a correlation between a plurality types of characteristics at
the same site of coin 20 can be detected. Accordingly,
discriminating circuit 47 can perform precise discrimination of
coin 20 including characteristics of the correlation at this same
site.
[0139] Moreover, since using switching control part 205, sensors
25, 26 are switched between the in-phase connection for detecting
the material of coin 20 and the reversed-phase connection for
detecting the thickness of coin 20, coin discriminating device 201
can be downsized, and a reduction in price can be achieved. These
effects are similar to the first exemplary embodiment.
[0140] Furthermore, in the present embodiment, since oscillating
part 204 oscillating in a self-exited manner is provided, frequency
divider 38 and the like can be omitted, which can realize a
configuration with less components as compared with the first
exemplary embodiment. Moreover, constant oscillation at the tuning
frequency allows a stable tuning state to be kept, thereby enabling
precise discrimination.
[0141] In the present embodiment, a similar configuration to third
switching part 93 shown in FIG. 6 may be applied to any one or more
of capacitors 71E to 71H, 221A, 221B so as to switch to a
capacitor(s) different in capacitance from capacitors 71E to 71H,
221A, 221B. This changes the oscillation frequency of oscillating
part 204, thereby bringing about similar effects to the second
exemplary embodiment. The configuration in which the materials of
coin 20A made of a plurality of metals are discriminated by
changing the oscillation frequency in this manner may be applied to
a coin discriminating device that does not perform magnetic
connection switching of sensor 25 and sensor 26.
[0142] While in these embodiments, the envelope waveforms are
formed in shaping part 94 (detecting circuit 45), the present
invention is not limited thereto. For example, by detecting output
voltages immediately before detecting circuit 45 is reset, or peak
values of the output voltages in a measurement interval, coin 20
can be discriminated.
INDUSTRIAL APPLICABILITY
[0143] Since a coin discriminating device according to the present
invention can sense a correlation between a material and a
thickness at almost the same site, thereby precisely discriminating
a coin, it is usable as a coin discriminating device mounted on a
vending machine or the like.
* * * * *